[FieldTrip] issue at interpolation after source analysis

Arjen Stolk a.stolk8 at gmail.com
Fri Mar 4 07:18:54 CET 2016


Hey Vitoria,

Hard to tell without seeing any code, but my hunch is that the plot on the
left is subject space whereas the middle is subject spaced data plotted in
MNI space. If the sourcemodel/grid on the left is truly MNI-aligned (but
the regular spacing suggests otherwise) than it may be an instance of
forgetting to copy over the dim and pos fields from the MNI template to the
subject mri structure. You can check whether this is case by comparing the
dim and pos fields of the template with those of the subject. They should
be the same (after alignment).

Hopefully that solves it. Otherwise you'd probably need to provide some
code.
Arjen

2016-03-03 21:28 GMT-08:00 Vitória Piai <v.piai.research at gmail.com>:

> Hi everyone,
>
> I'm working with clinical MEG data for which part of the source pipeline
> has been conducted by someone else as part of a clinical protocol. I don't
> have full access to what has been done to the MRI that I'm getting, so I'm
> trying to put bits and pieces of code together to arrive at a source
> reconstruction. The rest of my pipeline is the pretty standard tutorial
> beamforming.
>
> I was hoping someone could help me figure out where my source analysis is
> going wrong by looking at this figure. On the left, the subject's headmodel
> seems to be fine (after warping to MNI). On the right, I'm plotting the
> source result without interpolating with any structural data. In the middle
> you see what happens when I interpolate the source with the
> "single_subj_T1.nii" structural image.
> It doesn't seem to be a matter of scaling (like mm to cm), but rather it
> being kinda upside down + something else? Does anyone know by looking at
> this whether the error emerges because of an unsuccessful interpolation or
> because something more fundamental is going wrong earlier on?
>
> Thanks so much,
> Vitoria
>
>
>
>
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